Electric time fuse for blasting cartridges



Ja'm. 26, 1926. 1,570,733

W. ESCHBACH ELECTRIC TIME FUSE FOR BLASTING' CARTRIDGES Filed July 12, 1922 2 Sheets-Sheet 1 Inventor:

Jan. 26 1926. 1,570,733

' w. ESCHBACH ELECTRIC TIME FUSE FOR BLASTING CARTRIDGES Filed July 12, 1922 2 Sheets-Sheet 2 Fig.5. Fig.6.

Patented Jan. 26, 1926.

UNITED STATES WILHELM ESCHBACH, OF TROISDOBF, NEAR COLOGNE-ON-THE-RHINE, GERMANY.

ELECTRIC TIME FUSE FOR BLASTING CARTRIDGES.

Application an July 12, 1922. Serial No. 574,594.

. To all whom it may concern Be it known that I, WILHELM ESCHBACH, a citizen of Germany, residing at Troisdorf, near Cologne-on-the-Rhine, Germany, have invented a new and useful Improvement in Electric Time Fuses for Blasting Cartridges, for which I have filed applications in Germany February 5, 1922 E. 27,650 IV/7 8 e- Austria May 19/22-Gt. Brit, May 24/22.

Sweden June 1/22-Norway June 2/22- France June 9/22Japan, July 5/22S.

cut to different lengths corresponding with the desired intervals between the shots. The waste in the high-class material of the fuses caused hereby increases the costs of this process very considerably. A further disadvantage of this process is, that the fuse must be connected with the riming as well as with the blasting cartridge itself- It is obvious that it is very diflicult to make the connections perfectly tight. It therefore happens frequently that the priming or the blasting cartridge prepared according. to this process is rendered useless by the entrance of water which often collects in shot holes, especially as the combination of the blasting cartridge with the fuse is effected by the miners themselves in the mine. It is furthermore possible that inadvertently the primings are mixed up, so that the correct succession of the shots is disturbed and the effect of the entire set of shots is ren dered doubtful.

In mines liable to develop fire-damp the interval between the shots plays a part which must not be underrated. The shorter this interval, the lower is the chance that the dust raised by the first few shots or explosive gases liberated thereby become ignited by the subsequent shots.

Methods for firing a series of blasting shots by means of electric time-fuses are already known in which the beforementioned drawbac s of the hitherto u i g method in mining have been obviated. In the first case the formerly used fuse cords made of jute and gutta-percha, which were shortened or lengthened according to the intervals desired between the shots, were rendered completely unnecessary by the direct combination of the electric fuse with the blasting cartridge. The necessary intervals between the shots were obtained by retarding sets or tablets inserted into the blasting cartridges, in lace of the fuse cords. In order to allow t e gases develo ed during the i ition to escape closab e vents were provided laterally to the fuse which opened automatically under the action of the generated pressure.

This method offered undoubtedly some rather important advantages, which were, however, partly counterbalanced by a series of drawbacks. The large area of the vents, which was necessary in conse uence of the comparatively large volume 0 gas and the rather high temperature developed were found inconvenient. Furthermore the risk arises that the blasting cartridge becomes 30 excessively heated by the generated high temperatures and causes premature firing. This process also necessitated a very considerable quantity of retarding a cuts in order to bring about the desired mtervals 35 between the shots.

The object of my invention is to construct an electric time-fuse which is superior to the fuses hitherto in use and completely avoids their drawbacks. The improved fuse 99 forming the object of this invention completely satisfies all requirements.

The improved fuse is illustrated in the accompanying drawings in which Fig. 1 shows a set of five blasting cartridges in elevation,

Fig. 2 shows the same cartridges in longitudinal section and Figs. 3-9 various cartridges and methods of uniting the fuse cartridge with the blast- 109 ing cartridge. Similar parts are indicated by the same letters of reference throughout all the figures of the drawings.

Referring to Figs. 1 and 2 it will be seen that a set of shots consists of a number of blasting cartridges, for example five, of different lengths joined to electric time-fuses. It may here be mentioned that the length of the cartridge is an indication of the extent of the retardation of the ignition.

' fuses be asked for.

a is the insulated conducting wire of the shot-firing circuit, 6 the fuse cartridge, 0 the vent, which opens automatically under the action of the gas pressure, (1 the sulphur with which the fuse cartridge is. charged, e the primin or ignition head, f the nsertion piece with a central bore, contain ng the retarding agent and having a conical mouth, g the retarding set proper, h the charge of the blasting cartridge and i the shell of the blasting cartridge. The intervals between the shots represented in the drawings vary from 1/10 to one second.

By the employment of cylinders, the central bores of which contain the retarding sets or owder and the walls of which are made of aluminium, copper, iron or any other suitable metal, celluloid, paper pulp, textile fibers or any other suitable material, the volume of gas generated after the ignition is reduced to a minimum. In this manner the gas vents may on the one hand he made smaller and on the other hand a heating of the shell of the blasting cartridge proper-and thereby the risk of a premature 1gmtion is avoided. Instead of cylinders with central bores small tubes made of similar materials as the cylinders may be employed. Preferably the cylinder or tube is provided with a funnel-shaped expanded mouth, shown in the drawings opposite the ignition or firing point, whereby the reliable ignition of the retarding agent is ensured. While heretofore it was necessary to force the retarding agent into the blasting cartridge and the cartridge so built up was then supplied to the consumers combined with the fuse or priming cartridge, the cylinders or tubes may without risk be charged beforehand and be forced into the fuse or priming shell, which is subsequently combined with standard blasting cartridges. This process has, compared with the known ones, the advantage that electric fuses and blasting cartridges may be supplied to the consumers separately, without being obliged to adhere to this mode of manufacture should for some reason blasting cartridges combined with Furthermore it is also possible to house the retarding set in the blasting cartridge without being obliged to abandon the separate supply of the parts.

The primin cartridge may be combined with the blasting cartridge in various ways, some of which are'illustrated in the drawings, by way of example. So may for instance, a projection-k be fixed upon the shell of the blasting cartridge, which is adapted to be slid into a longitudinal groove Z upon the priming cartridge, whereupon the two parts are turned relatively to each other, see

Figs. 7-9. It will be understood that the transport is greatly facilitated by the possibility of supplying the parts separately,

whether the retarding agent be housed in the priming cartridge or in the blasting cartridge. The vents can, if the retarding agent is housed in the priming cartridge, be provided in the sides of the priming cartridge between the retarding device and if the ignition head or preferably parallel to the longitudinal axes of the primin cartridge. Four such constructions are clearly shown in the Figs. 3-6 of the drawings.

In Fig. 3 retarding tablets n are provided in the priming cartridge and in Fig. 4, a loose retarding set. In Figs. 5 and 6 the ignition cartridge is fitted with a retarding insertion piece 7 and in Figure 5 it is guided internally in the blasting cartridge and in Figure 6, it surrounds the blasting cartridge externally.

As a retarding agent any suitable sub stance may be employed, for instance black powder, nitrocellulose, lead picrate, lead hexaminate and the like and also special sets, which may consist of potassium chlorate, charcoal and infusorial earth or potassium chlorate, tetranitromethylaniline and infusorial earth or similar compositions. The here by way of example mentioned retarding sets and compositions are as a matter of course not meant as a limitation and by no means exclude the use of other agents not stated, either singly or several in combination. The intervals between the shots may be determined in various ways. Beginning with the instantaneous fuse shown at the left of Figs. 1 and 2 various intervals may ad infinitum be produced by a series of blasting cartridges, which can be distinguished by their lengths. For the sake of simplicity only 5 lengths of cartridges are shown in the drawings, but it will be readily understood that any convenient number may be employed. As a matter of course the succession of shots may be indicated by numbers upon the cartridge shells or by differently coloured shells.

What I claim as my invention and desire to secure by United States Letters Patent is:

In combination, in separate casings, a blasting cartridge and a fuse cartridge, a retarding element interposed between the fuse cartridge and the blasting cartridge, 3. priming head positioned at the inner end of the fuse cartridge, a free air space, substantially equal to thefuse cartridge, being left between the priming head and the blasting eartridge, and a vent in the fuse cartridge near 20 one edge thereof cannecting the said free air space with the atmosphere whereby to carry the gases away from the shot in order to prevent pre-ignition.

In testimony whereof I have hereunto set my hand.

W ELM ESGHBAGH. 

